Essential disadvantages of PPU insulation:
- The thermal resistance of PPU insulation does not exceed 130 0С (only a short-term increase of the coolant temperature up to 1500С is allowed). This factor significantly limits the use of PPU insulation in thermal networks operating on temperature graphs of 140 / 700C, 150 / 700C and above. Work on temperature graphs 140 / 700С, 150 / 700С and above, for thermal networks in polyurethane foam insulation is possible only if there is a special heat-insulating layer (thin polymer concrete or anticorrosion coating "Vector-1265") that separates the main layer of PPU insulation and the outer wall pipeline. This technology is called "steel pipe in combined PPU insulation."
- Thermal insulation of polyurethane foam is weak and has a weak resistance to mechanical influences (compressive strength does not exceed 0.3-0.4 MPa and only partially meets the requirements of SNiP 41-03-2003 "Thermal insulation of equipment and pipelines").
- When the foam is wetted, the insulation is destroyed and can have an aggressive corrosive effect on the pipelines. This factor stipulates the mandatory use of a hydro-protective coating (a layer of high-density polyethylene) and a system of operatively remote control (PODC) behind the moistening of polyurethane foam insulation.
- If the foam insulation is damaged and / or humidified, the entire section of the heat network (ie PPC insulation, not repairable-fit) is completely replaced.
- Thermal insulation of polyurethane foam combustible (ie heat-insulating material is fire-hazardous).
- High cost of thermal insulation structures made of polyurethane foam: more than the cost of APB insulation and insulation from mineral wool in 1,2 ... 1,8 times.
- The need for continuous monitoring of the moisture of the polyurethane foam insulation (ie the pipelines of heating networks in polyurethane foam insulation must be equipped with a system of operatively remote monitoring of the humidity of the insulation).